They missed the whole celebration 45 years ago this Sunday. So did Michael Collins, orbiting solo around the moon in the mother ship.

Now, on this Apollo 11 milestone Aldrin is asking everyone to remember where they were when he and Armstrong became the first humans to step onto another heavenly body, and to share their memories online.

Too young? You can also share how the moonwalkers inspired you.

Celebrities, public figures, and other astronauts and scientists are happily obliging with videos.

It's the first big anniversary of man's first moon landing without Armstrong, whose "one small step … one giant leap" immortalized the moment.

Armstrong, long known for his reticence, died in 2012 at age 82.

As Apollo 11's commander, Armstrong was first out the lunar module, Eagle, onto the dusty surface of Tranquility Base. Aldrin followed.

Collins, now 83, the command module pilot who stayed behind in lunar orbit as the gatekeeper, also spent decades sidestepping the spotlight. He's making an exception for the 45th anniversary — he plans to take part in a NASA ceremony at Kennedy Space Center on Monday to add Armstrong's name to the historic Operations and Checkout Building.

That leaves Aldrin, 84, as the perennial spokesman for Apollo 11. He will also be at Monday's ceremony.

"The whole world celebrated our moon landing. But we missed the whole thing because we were out of town. So now I invite you to share with me — and the world — your story or your family's story of where you were on July 20th, 1969. Or feel free to tell me how the Apollo missions inspired you."

Aldrin is asking people to post a video to YouTube using the hashtag #Apollo45.